Arc chute including splitter plates having interengaging portions



. Sept. 28, 1965 R. G. COOPER ETAL ARC CHUTE INCLUDING SPLITTER PLATES HAVING INTERENGAGING PORTIONS Filed April 17. 1961 2 Sheets-Sheet 1 2 1,46 l m x L Pd l 20c 2 Y! IN V EN TORS ROBERT G. COOPER GORD 0. PERKINS m f. Mm

ATTORNEYS Sept. 28, 1965 R. G. COOPER ETAL 3,209,108

ARC CHUTE INCLUDING SPLITTER PLATES HAVING INTERENGAGING' PORTIONS Filed April 17, 1961 2 Sheets-Sheet 2- 12 FIG. 5

INVENTORS ROBERT C. COOPER GORDON O. PERKINS BY wf iw.

ATTORNEYS United States Patent 3,209,108 ARC CHUTE INCLUDING SPLITTER PLATES HAVING INTERENGAGING PORTIONS Robert G. Cooper, Rockaway, Ni, and Gordon 0. Perkins, Cannonsburg, Pa., assiguors to Federal Pacific Electric Company, a corporation of Delaware Filed Apr. 17, 1961, Ser. No. 103,321 8 Claims. (Cl. 200-144) This invention relates to circuit interrupting devices and more particularly to are chutes for circuit breakers.

When air breakers are used with high current densities, and paticularly with high voltages, arcs having explosive force are generated. The are chute is required to withstand such forces and to confine the hot ionized gases 'during the extension of the arc as it approaches exhaust ports remote from the contacts where the arc originates.

Arc chutes utilizing arc splitter plates have been fabricated from insulating material such as a mixture of asbestos and Portland cement, of mica-impregnated compositions, etc., the stacked splitter plates being contained within an additional housing made of insulating material.

It is an object of this invention to provide an improved arc chute for air-break circuit interrupters.

It is a further object of this invention to provide a novel are chute having interlocking self-supporting and selfaligning arc splitters.

Another object of this invention resides in an arc chute having reversible interlocking arc splitter plates, which are interchangeably righ or left, and which stretch the are into zig-zag segments.

A further object of this invention resides in the provision of an arc chute comprising independent interlocked arc splitter plates of improved construction which are chute will contain arc-generated gases within the arc chute without depending upon secondary housing wall structure.

A further object of this invention is to provide an arc splitter plate provided with interlocking features so that an arc chute may be assembled from individual identical plates by stacking without resort to separate spacers.

In the illustrative embodiment of this invention that is described in detail below, the arc splitter plates have flanges extending along a web, the flanges being of stepped interlocking form to confine and contain the high-pressure arc gases without dependence upon side walls of the arc chute and without exposure of any such side walls to hightemperature are products. At one level the illustrative splitter plates is of I-shaped cross-section having one broad, stepped flange at one edge of a web and a narrow flange at the opposite edge of the flange. At another region, the web has only one flange that is of stepped configuration complementary to the adjacent duplicate splitter plates of the stack.

The abovementioned and other objects, advantages and novel features of the invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an end view of a circuit breaker showing a pair of circuit-interrupting contacts and an associated arc chute;

FIG. 2 is a top view of a central portion of the arc chute shown in FIG. 1 illustrating interlocking features at that end of the chute;

FIG. 3 is a plan view, in section, of a portion of the chute similar to that in FIG. 2 taken along the line 33 of FIG. 1 and illustrating an interlocking feature at the lower end of the chute;

FIG. 4 is an exploded view of a portion of the circuit breaker and'arc chute of FIG. 1; and,

.plate 100.

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FIG. 5 is a perspective view of an individual are split ter plate.

An arc chute fabricated according to the teachings of one aspect of the invention comprises a plurality of stacked arc splitter plates 10. Referring particularly to FIG. 5, an arc splitter plate 10 has a generally I-shaped cross-section formed by a web 16 that has a full length wide flange 12 anda shorter narrow flange 14. The upper end 18 of the plate framed by the narrow or short flange 14 and wide flange 12 may be characterized as rectangular. Stepped portion 20 is adjacent'the wide flange 12 and projects equally from both sides of web 16. The overall width W of the stepped portion 20 (FIG. 2) is equal to the width w of the narrow flange 14. The height of the step portion 20 is equal to the thickness of the narrow flange 14. Narrow flange 14 extends from the upper end 18 of the plate toward the center where it terminates sharply at a notch 22 transverse the plate. The width of the lower end 21 of web 16 is sharply reduced by notch 22 at the end of the narrow flange 14. The stepped portion 20 at one face of web 16 is replaced by a rib 24 that projects beyond the edge of the stepped portion 20 by a distance equal to the width of the narrow flange 14. Rib 24 rises sharply from step 20 at a point directly opposite the end of the narrow flange 14. The length of rib 24 when added to the'length of narrow :flange 14 is equal to the length of wide flange 12. The lower end portion 21 of Web 16 tapers gradually from notch 22 toward the lower end 26 of the plate.

A plurality of arc splitter plates 10 are assembled into an arc chute 28 as part of a circuit breaker 30 which includes a fixed contact 32 and a relatively movable contact 34 having arcing tips 36, 37 respectively. The plates 10 are supported in position by sidewalls 38 and endwalls 39. A conventional magnetic blow-out device (not shown) may be added to the arc chute illustrated, and operating mechanism having overload release means (not shown) will also be included as part of the complete circuit breaker.

Referring to FIG. 2, the arc chute 28 is formed by stacking a plurality of identical, individual plates 10. First plate 10a and third plate are assembled with their wide flanges 1 2a and 12c touching. The second .plate 10b is inserted between the first plate 10a and third The short flange 14b of the second plate is received in a recess formed by the wide flange 12c and end of rib 240 of the third plate 100 and wide flange 12a of the first plate 10a (FIG. 2). When the second plate 10b is in position, the short flanges 14a and 14c of the first and third plates 10a and 100 abut opposite sides of step 20b and bottom against the opposite sides of wide flange 12b of the second plate 10b. The lower end of short flange .140 of the third plate abuts the upper end of the .rib 24b of the second plate 10b. Along its length, rib 24c (FIG. 3) is in face contact with flange 12a and in edgewise contact with step 20a. This stacking arrangement is repeated until the desired length of chute has 'been fabricated. The flanges 12, 14, stepped portions 20, and ribs 24 provide complementary mutually engaging integral formations along the longitudinal edges of the splitter plates. The completed chute has side plates 38 and end plates 39 covering assembled flanges 12, and is mechanically held together and mounted by conventional means.

The configuration of the individual plates is such that neither specialized right and left plates are needed,

When the circuit breaker contacts 36, 38 separate an arc is struck. It travels upwardly into the chute and expands as a loop, the length of the are increasing rapidly. The alternating edges of lower plate portions 21 force the arc to assume a zig-zag configuration (FIGS. 1 and 3). When the arc reaches the web notch 22, the arc is subdivided into segments as it continues to rise. The lengthening of the arc plus the cooling occasioned by the proximity of the plates 10 causes the arc to be extinguished by the time it reaches the upper end of the chute.

The multiple overlaps of the wide and narrow flanges 12, 14 of the plates 10 in the upper end 18 of the chute 28 provide sharp breaks in any residual passageways that may extend between the interior and exterior of the chute, for effectively confining the arc-generated gases and for cooling any small flow of gas which might escape at the sides of the arc chute. The overlapping ribs 24 and wide flanges 12 of the lower end of the chute, also inhibit escape of gases from the interior to the exterior of the chute 28 without depending upon a secondary surrounding housing.

The hereinbefore described are splitter plate and assembly of arc splitter plates to constitute an arc chute is readily adaptable to any length of plate or size of chute without losing the recited advantages. Although only one embodiment of the invention has been shown and described, it will be apparent to those skilled in the art that various changes, modifications and varied application of its novel features may be made by those skilled in the art without departing from the scope of the invention.

What we claim is:

.1. An arc chute comprising a stacked assembly of a large number of individual arc splitter plates having mutually separated web portions providing arc-quenching spaces therebetween, said splitter plates having means including complementary mutually engaging integral formations along longitudinal edges thereof providing at least two sharp stepped bends in any are leakage path from each arc-quenching space to the external lateral surface collectively defined by the stacked plates.

2. An arc chute comprising an assembly of individual arc splitter plates including first, second and third are splitter plates stacked in the sequence named and having mutually separated web portions, said first and third are splitter plates having respective relatively wide integral longitudinal flanges in mutual edge-to-edge abutment, said second splitter plate having a relatively narrow longitudinal integral flange, and said flanges of said first and third splitter plates embodying step formations cooperating with the flange of said sec-nd arc splitter plate to dispose a longitudinal portion of said second plate in face contact with both said wide flanges where the latter are in abutment, the overall width of said step portion being equal to that of said narrow flange and the projection of said wide flange ibeyond said step portion being equal to 'half the width of said narrow flange, and each flange being symmetrical about the plane centered in its respective web.

3. An arc splitter plate including a web having longitudinal edges, a wide flange along one edge of the web and a narrow flange along the opposite edge, said wide flange having a step portion at each face of the web, the overall width of the step portion being equal to the width of said narrow flange and the Wide flange projecting later- .ally beyond said step portion by half the overall width of said narrow flange.

4. An arc splitter plate including a web having a relatively narrow longitudinal flange along one edge and a relatively wide longitudinal flange on the opposite edge, :said wide flange having a stepped portion on each side of the web, the overall width of said stepped portions being equal to the width of said narrow flange, said stepped portions separating the narrow flanges of like splitter plates when late ally assembled to said arc splitter plate, said wide flanges overlapping said narrow flanges so as to interrupt direct-path leakage of pressure gases past said wide flange.

5. An arc splitter plate including a Web, one portion of the web having .a first flange along one edge, said one portion having a second flange along the opposite edge of said one web portion, said second flange being of a greater width than said first flange, each side of said wide flange being stepped and being of shape complementary to a corresponding side of said first flange, said web having another portion narrower than said one web portion and having a third flange extending integrally from and in line with said second flange, said third flange being of the same cross-section as said second flange but having an integral laterally projecting rib, the laterally projecting rib having one end in transverse alignment with one end of said first flange and said rib being of the same Width measured from said step portion as said first flange.

'6. An arc splitter plate including integral upper and lower adjoining portions, the upper portion being of generally I-shaped cross-section including a web portion having longitudinal edges, a relatively wide flange along one edge of said upper portion of the web and a narrow flange along the opposite edge of said upper portion of the web, said wide flange having a step portion extending at the opposite sides of said web, the width of said step portion being equal to the overall width of said narrow flange, and said relatively wide flange projecting laterally at both sides of said step portion by an aggregate extent equal to the width of said narrow flange, the lower portion of the web having a flange along one edge, the latter flange extending integrally from the wide flange of the upper portion of the web, said lower portion of the web being narrower than said upper portion, said extending part of said relatively Wide flange having an integral laterally projecting rib whose upper end is transversely aligned with the lower end of said relatively narrow flange and whose width measured from said step portion is equal to that of said relatively narrow flange.

7. An arc chute comprising at least first, second, and third are splitter plates, each of said plates including a Web having a relatively narrow flange along one edge and a second flange of a greater width along the opposite edge, said second flange having a step portion whose width equals that of said narrow flange and said second flange extending equally on both sides of said step portion, said narrow flange extending from one end of said plate and only partway along said plate, an integral rib formed on one side of said step portion starting at a point opposite the lower end of said narrow flange and extending to the opposite end of said plate, the width of said rib portion measured from said step portion being equal to that of said narrow flange, the extending portions of the wide flanges of said first and third plates being in edgewise abutting relationship, the step portion of said first plate and the step portion and rib of said third plate defining a recess in which the narrow flange of said second plate is received, and the narrow flanges of said first and third plates abutting opposite sides of the stepped portion of said second plate thereby to constitute tw-o sharp stepped bends in any gas leakage path from the arc-quenching space between abutting arc splitter plates and the external surface defined by said abutting wide flanges.

8. An arc chute comprising at least first, second, and third are splitter plates, each of said plates having a generally I-shaped cross-section with a narrow flange of a given width and an opposed flange of a greater width with a web of a given depth extending therebetween, said web having a step portion of an overall width equal to said given width formed adjacent said wider flange and extending equally on both sides of said web, said narrow flange extending from one end of said plate and terminating at a point adjacent the middle of said plate, an integral rib formed on one side of said step portion starting at a point opposite the end of said narrow flange and extending to the further end of said plate, the Width of said rib portion measured from said step portion being equal to said given Width, the depth of said web tapering from the end of said narrow flange to the further end of said plate, said wide flanges of said first and third plates being in edgewise abutting relationship, the step portion on said first plate cooperating with the step portion and the end of the rib of said third plate to delimit a recess for receiving the narrow flanges of said second plate, the narrow flanges of said first and third plates abutting opposite sides =0f the stepped portion of said second plate, and the end of the narrow flange of said third plate abutting the end of the rib of said second plate.

References Cited by the Examiner UNITED STATES PATENTS 1,422,481 7/ 22 Schenkel et a1. 200144 2,073,565 3/37 Ruppel Z00149 2,564,178 8/ 5'1 Strobel 200--144 2,759,073 8/5 6 Wood ZOO-144 2,941,060 6/ 60 Caswell 200144 FOREIGN PATENTS 729,429 5/55 Great Britain,

BERNARD A. GILHEANY, Primary Examiner.

MAX L. LEVY, ROBERT K. SCHAEF-ER, Examiners. 

1. AN ARC CHUTE COMPRISING A STACKED ASSEMBLY OF A LARGE NUMBER OF INDIVIDUAL ARC SPLITTER PLATES HAVING MUTUALLY SEPARATED WEB PORTIONS PROVIDING ARC-QUENCHING SPACES THEREBETWEEN, SAID SPLITTER PLATES HAVING MEANS INCLUDING COMPLEMENTARY MUTUALLY ENGAGING INTEGRAL FORMATIONS ALONG LONGITUDINAL EDGES THEREOF PROVIDING AT LEAST TWO SHARP STEPPED BENDS IN ANY ARC LEAKAGE PATH FROM EACH ARC-QUENCHING SPACE TO THE EXTERNAL LATERAL SURFACE COLLECTIVELY DEFINED BY THE STACKED PLATES. 